In the United States, the accuracy level at which commercial fuel dispensing mechanisms must operate is controlled by federal and/or state regulations. Such regulations now permit a tolerance in the sales cost read-out of a mechanical fuel pump counter that is equal to one-half of the smallest increment effectively displayed on the lowest digit number wheel; it is therefore desirable to limit the display to the largest allowable incremental value. Presently, a one-cent increment is required for fuel unit volume prices of less than one dollar per gallon; two-cent increments are permitted for prices of from one dollar to less than three dollars per gallon; and five-cent increments are allowed for prices of three dollars and higher. Due to pricing uncertainties and expected increases in the cost of fuel, it is desirable to provide means that will obviate the necessity for fundamental equipment modification, to accommodate such fluctuating prices, or by which the need for making such modifications can at least be delayed, so as to thereby minimize the inconvenience and expense entailed.
In U.S. Pat. No. 4,347,435, Evans et al disclose readout mechanisms for fuel pump counters, in which means is provided for selectively masking the short graduations on the lowest order number wheel, to enable selective reading in either one- or two-cent graduations. While the description of the patent is primarily concerned with the provision of mask means that is selectively mountable by the read mechanism mounting means, other alternatives are disclosed. For example, the patentees suggest use of a wheel having colored increment graduation lines, which can be obscured by a similarly colored transparent mask. However, all approaches disclosed by Evans et al (other than perhaps, that of simply employing a masking tape on the wheel rim) are somewhat complex, and would not appear to be subject to implementation as conveniently as might be desired.
Accordingly, it is an object of the present invention to provide novel means for effectively converting the display of the lowest digit number wheel of a mechanical counter for fuel dispensing mechanisms, which does not necessitate any fundamental or substantial change in the equipment.
It is a more specific object of the invention to provide such means by which lower order and higher order indicia on a single counter wheel can be selectively displayed.
It is also an object to provide such means which is simple, convenient, and relatively inexpensive to produce and to implement.